Marco B41CF - Hearth Extensions Installation

I FIREPLACE FLUSH WITH WALL
ri,
(HEAT CIRCULATING MODEL SHOWN)
11
I*
LOUVRES
ROOM AIR -^a
- ?,
-- - -
IX IHSULATED
' PLATFORM
-
SUBFLOOR
HEARTH EXTENSION Figure
HEARTH EXTENSIONS:
IT!hcreis acornbt~stihlefloorconsfruction in frorilofthr. fireplnce,
yo11 are r~qllired 10 protect it with a hearth extension. The hearth
extension, as
show11 in Figurr 36; lnusl be a minimum of 16 inclirs
deep by 51 inchcs wide. and extend n tnit~im~irn of 8" bryorid each
sidc of the fircpl;~ce opening.
The hearth rxtrnsion must be made from a non-combustible
inorganic material wit11 a tllrrrnnl conductivity, K, of 43 or less.
The
tl~ern~al conductivity, K, or themla1 resistance, R, of materials
can usually be
obtair~ed from the manufacturer. The factors arc
rclatzd by the formula K- 1/R The thickness required for various
conuilon niateria!~ and tllrir f;iclorr are showrr in Figure 37.
Minimum
Type
of Insulation I K* I Tllicb Required /
Johns Manville
1 CFKAPORM 126 I 27 62
I
U.S. Gypsum COT.
MICORE CV230
Insulating Board
(K-FAC 19)
Lydall, Inc.
LYTHERM 1401
Standard Oil
DURABOARD
LD and HD
*Units of K are BTU/HR FT OF
I
!
Industrial
Insulation,
Inc.
MAXFIRE 2400
FIGURE 37 -- COMJfOh' MATERIALS
AKD THEIR FACTORS
.64
.60
.SO
1.48
1.39
f i r e - p a r t s . c o m